Diphosphites

ABSTRACT

A diphosphite is provided derived from phosphorous trihalide, tetra alkyl hindered bisphenol, and a neoalkyl diol. The phosphites exhibit improved stability and are useful as thermal oxidative stabilizers for thermoplastic compositions.

This is a divisional of application Ser. No. 08/538,372 filed on Oct. 5,1995, U.S. Pat. No. 5,618,961 which is a continuation of applicationSer. No. 08/096,107 filed on Jul. 22, 1993, now U.S. Pat. No. 5,523,448.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to diphosphites, and more particularly relates toneoalkyl diphosphites.

2. Description of the Related Art

Diphosphites of the formula: ##STR1## wherein Y is a divalent radicalselected from the group consisting of: ##STR2## R is independentlyselected from the group consisting of hydrogen, alkyl of 1 to 6 carbonatoms, preferably of 1 to 4 carbon atoms, and halogen, preferablychlorine or bromine; R¹ is independently selected from the groupconsisting of hydrogen, alkyl of 1 to 12 carbon atoms, preferably from 1to 6 carbon atoms, R² is independently selected from the groupconsisting of hydrogen, alkyl of 1 to 12 carbon atoms, preferably of 1to 9 carbon atoms, and halogen, preferably chlorine or bromine; and R³is independently selected from the group consisting of alkyl of 1 to 12carbon atoms, preferably of 1 to 9 carbon atoms, and halogen, preferablychlorine or bromine, see Dever et al. U.S. Pat. No. 3,467,733 which isincorporated herein by reference. Dever et al. teaches that thediphosphites may be obtained by reacting a cyclic phosphorohalidite ofthe formula: ##STR3## wherein R is as previously mentioned, and A ishalogen, preferably chlorine or bromine, and lists5-butyl-5-ethyl-2-chloro-1,3,2,-dioxaphosphorinane, with a hydroxyorganic compound of the formula: ##STR4## wherein R¹, R², and R³ are aspreviously mentioned, and lists 2,2-bis(4-hydroxyphenyl) propane amongothers. While some of these phosphites find utility as stabilizers forpolymers, it is desired to improve their hydrolytic and ultravioletlight stability.

Consequently, the present invention provides a diphosphite exhibitingimproved stability.

SUMMARY OF THE INVENTION

The present invention provides a phosphite of the formula: ##STR5##wherein R⁴, R⁵, R⁶ and R⁷ are as defined below. The diphosphites areuseful as stabilizers for organic materials such as thermoplasticpolymers and exhibit improved hydrolytic and ultraviolet stability.

DETAILED DESCRIPTION OF THE INVENTION

The diphosphites are represented by the formula: ##STR6## wherein eachR⁴ is independently selected from the group consisting of hydrogen andalkyl radicals of 1 to 6 carbon atoms, preferably of 1 to 4 carbon atomsmore preferably hydrogen or t-butyl, and optionally halogen, preferablychlorine or bromine, each R⁵ is an alkyl group, preferably having from 1to 6 carbon atoms, each R⁶ is independently selected from the groupconsisting of alkyl radicals of 1 to 6 carbon atoms. R⁷ is a divalentradical, and is preferably a divalent alkylidene having from 1 to 6carbon atoms such as isoproylidene. Optionally R⁷ may be a direct bond,or R⁷ may be a sulphur group or an oxygen group or an organo siloxanegroup.

The diphosphites may be obtained from the following reactants: a)phosphorous trichloride (PCl₃) or a phosphite ester (P(OR⁸)₃) whereineach R⁸ is a hydrocarbon radical preferably selected from the groupconsisting of alkyl and aryl groups, b) neoalkylene glycols, and c) thehydroxy organic compound is tetra alkyl hindered bisphenolic like2,2-bis(4-hydroxy-3,5-di-t-butyl phenyl) propane. The neoalkylene glycolmay be reacted with the phosphorous trichloride to form aphosphorohalidite which can then be reacted with the tetra alkylhindered bisphenolic such as (2,2-bis(4-hydroxy-3,5-di-t-butylphenyl)propane) to yield the desired diphosphite.

A nitrogen-containing compound or acid acceptor may be utilized toneutralize the reaction product, there may be utilized triethylamine,tributylamine, tripropylamine, pyridine, dimethylamine, and the like. Ifdesired, a hydrocarbon solvent may be utilized.

The reaction between the cyclic phosphorohalidite and hydroxy organocompound may be effected by mixing the reactants together at roomtemperature, or, if necessary, by heating the mixture of reactants tomoderately elevated temperatures. The reaction can be carried out mostconveniently at atmospheric pressures. However, if preferred, pressureseither higher or lower than atmospheric may be employed.

Relative amounts of the reactants employed are not critical, although itis desirable that an excess of hydroxy compound be avoided. It ispreferred that the cyclic phosphorohalidite and hydroxy organic compoundbe present in the reaction zone in about stoichiometric proportions.

When a molar proportion of dihydroxy organic compound is reacted,substantially two molar proportions of cyclic phosphorohalidite areemployed, however, an excess of up to five or more molar proportions mayalso be utilized. The nitrogen-containing acid acceptor is added to thereaction product in substantially molar proportions based upon thequantity of cyclic phosphorohalidite utilized. However, it is within thescope of the invention to employ an excess of nitrogen-containing acidacceptor.

In conducting the reaction, the total amount of cyclicphosphorochloridite and hydroxy organic compound may be charged to areaction vessel initially. The reaction times may vary, but generallytime in the range of one to eight hours is sufficient to complete thereaction. Following this initial reaction, the nitrogen-containing acidacceptor may be introduced to the reaction vessel in any suitablemanner. The introduction of nitrogen-containing compound is generallycompleted in times ranging from one to six hours.

The reaction mixture can be worked up in any suitable manner. It ispossible, for instance, to remove the solid constituents by filtration.If a solvent is employed in the reaction, it may be removed bydistillation, evaporation or by any other suitable method. Because ofthe high yields which are in many cases obtainable, separation of thedesired cyclic diphosphite, following filtration and solvent removal, isnot always required for utility of the product and in such cases may bedispensed with. However, if separation is desired, techniques such asdistillation, extraction, crystallization, or the like, may be employed.

The diphosphites are useful as stabilizers for polymeric materialsincluding polypropylene, polyethylene, polycarbonate, polyethyleneterephthete, polybutylene terephthalate, polyphenylene ethers,polystyrene, acrylonitrile-butadiene-styrene, EPDM rubber, polyurethanesand polyamides. Optionally, the material is a polypropylene, which maycontain a residual catalyst such as titanium catalyst on a magnesiumhalide carrier. The phosphite is preferably present in the polymericcomposition at a level of from 0.01 percent by weight to 1 percent byweight based on the total weight of the composition.

Thermoplastic compositions containing a polymer and an amount of thepresent phosphite can be made by blending. The phosphites of thisinvention are effective antioxidants which may be employed in a widerange of organic polymers. Polymers which can be stabilized include:

1. Polymers which are derived from mono- or diolefins, e.g.,polyethylene which can optionally be crosslinked, polypropylene,polyisobutylene, polymethylbutene-1, polymethylpentene-1, polyisoprene,polybutadiene.

2. Mixtures of the homopolymers cited under (1), for example mixtures ofpolypropylene and polyethylene, polypropylene and polybutene-1,polypropylene and polyisobutylene.

3. Copolymers of the monomers based on the homopolymers cited under (1),for example ethylene/propylene copolymers, propylene/butene-1copolymers, propylene/isobutylene copolymers, ethylene/butene-1copolymers as well as terpolymers of ethylene and propylene with adiene, for example hexadiene, dicyclopentadiene or ethylidenenorbornene, and copolymers of α-olefins, e.g., ethylene, with acrylic ormethacrylic acid.

4. Polystyrene.

5. Copolymers of styrene and of α-methylstyrene, for examplestyrene/butadiene copolymers, styrene/acrylonitrile copolymers,styrene/acrylonitrile/methylacrylate copolymers,styrene/acrylonitrile/acrylic ester copolymers, styrene/acrylonitrilecopolymers modified with acrylic ester polymers to provide impactstrength as well as block copolymers, e.g., styrene/butadiene/styreneblock copolymers.

6. Graft copolymers of styrene, for example the graft polymer of styreneto polybutadiene, the graft polymer of styrene with acrylonitrile topolybutadiene as well as mixtures thereof with the copolymers citedunder (5), commonly referred to as acrylonitrile/butadiene/styrene orABS plastics.

7. Halogen-containing vinyl polymers, for example polyvinyl chloride,polyvinylidene chloride, polyvinyl fluoride, polychloroprene,chlorinated rubbers, vinyl chloride/vinylidene chloride copolymers,vinyl chloride/vinyl acetate copolymers, vinylidene chloride/vinylacetate copolymers.

8. Polymers which are derived from α,β-unsaturated acids and derivativesthereof, polyacrylates and polymethacrylates, polyacrylic amides andpolyacrylonitrile.

9. Polymers which are derived from unsaturated alcohols and amines andfrom the acyl derivatives thereof or acetals, for example polyvinylalcohol, polyvinyl acetate, polyvinyl stearate, polyvinyl benzoate,polyvinyl maleate, polyvinyl butyral, polyallyl phthalate, polyallylmelamine and copolymers thereof with other vinyl compounds, for exampleethylene/vinyl acetate copolymers.

10. Homopolymers and copolymers which are derived from epoxides, forexample polyethylene oxide or the polymers which are derived frombis-glycidyl ethers.

11. Polyacetals, for example polyoxymethylene, as well aspolyoxymethylenes which contain ethylene oxide as comonomer.

12. Polyalkylene oxides, for example polyoxyethylene, polypropyleneoxide or polyisobutylene oxide.

13. Polyphenylene oxides.

14. Polyurethanes and polyureas.

15. Polycarbonates.

16. Polysulphones.

17. Polyamides and copolyamides which are derived from diamines anddicarboxylic acids and/or from aminocarboxylic acids or thecorresponding lactams, for example polyamide 6, polyamide 6/6, polyamide6/10, polyamide 11, polyamide 12, poly-m-phenylene-isophthalamide.

18. Polyesters which are derived from dicarboxylic acids and dialcoholsand/or from hydroxycarboxylic acids or the corresponding lactones, forexample polyethylene glycol terephthalate,poly-1,4-dimethylol-cyclohexane terephthalate.

19. Crosslinked polymers which are derived from aldehydes on the onehand and from phenols, ureas and melamines on the other, for examplephenol/formaldehyde, urea/formaldehyde and melamine/formaldehyde resins.

20. Alkyd resins, for example glycerol/phthalic acid resins and mixturesthereof with melamine/formaldehyde resins.

21. Unsaturated polyester resins which are derived from copolyesters ofsaturated and unsaturated dicarboxylic acids with polyhydric alcohols aswell as from vinyl compounds as crosslinking agents and also thehalogen-containing, flame-resistant modifications thereof.

22. Natural polymers, for example cellulose, rubber, as well as thechemically modified homologous derivatives thereof, for examplecellulose acetates, cellulose propionates and cellulose butyrates andthe cellulose ethers, for example methyl cellulose.

The phosphites of this invention are particularly effective instabilizing organic materials such as thermoplastic polymers, inaddition to mineral and synthetic fluids such as lubricating oils,circulating oils, etc.

The phosphites of this invention are particularly useful as stabilizers,especially for the protection of polyolefins, for instance,polyethylene, polypropylene, polyisobutylene, poly(butene-1),poly(pentene-1), poly(3-methylbutene-1), poly(4-methylpentene-1),various ethylene-propylene copolymers and the like.

Other polymers in which the phosphites of this invention areparticularly useful are polystyrene, including impact polystyrene, ABSresin, SBR, isoprene, as well as natural rubber, polyesters includingpolyethylene terephthalate and polybutylene terephthalate, includingcopolymers. Other suitable polymers include polyurethanes,polycarbonates, polyamides such as nylon 6, 6/6 and the like as well ascopolyamides and polysulfones.

The phosphites may be used with primary stabilizers such as phenolicantioxidants, a neutralizer such as calcium stearate, pigments,colorants or dyes, UV absorbers, light stabilizers such as hinderedamines, metal deactivators, talc and other fillers, etc. Preferably thephosphites should be used in polymeric compositions in combination witha phenolic antioxidant and a neutralizer.

In general, the phosphites of this invention are employed at from about0.01 to about 5% by weight based on the total weight of the stabilizedthermoplastic composition, although this will vary with the particularpolymer and application. An advantageous range is from about 0.05 toabout 2% by weight thereof, and especially 0.1 to 1% by weight thereof.

The phosphites of this invention stabilize polymers especially duringhigh temperature processing with relatively little change in color, eventhough the polymer may undergo a number of extrusions. Among thepolymers in which this property is especially important arepolypropylene, polyethylene, styrenics such as ABS, polyethylene- andpolybutylene-terephthalates, polycarbonates, natural rubber, syntheticrubber such as SBR. These phosphites can be used as process stabilizersfor polyolefins in the presence of costabilizers such as phenolicantioxidants. A particularly important property for stabilizers whichare trivalent phosphorous esters is resistance to hydrolysis in thepresence of moisture in the atmosphere during ambient storage.Hydrolysis of the phosphorous esters during storage frequently resultsin compounds which are less effective. The phosphites of the presentinvention exhibit hydrolytic stability. The phosphites of the presentinvention also exhibit resistance to UV yellowing.

The phosphites of the present invention may readily be incorporated intothe organic polymers by conventional techniques, at any convenient stageprior to the manufacture of shaped articles therefrom. For example, thestabilizer may be mixed with the polymer in dry powder form, or asuspension or emulsion of the stabilizer may be mixed with a solution,suspension, or emulsion of the polymer. The stabilized polymercompositions of the invention may optionally also contain variousconventional additives, such as the following:

1. Antioxidants

1.1 Simple 2,6-dialkylphenols, such as, for example,2,6-di-tert.-butyl-4-methylphenol, 2-tert-butyl-4,6-dimethylphenol,2,6-di-tert.-butyl-4-methoxymethylphenol and2,6-dioctadecyl-4-methylphenol.

1.2 Derivatives of alkylated hydroquinones, such as, for example,2,5-di-tert.-butyl-hydroquinone, 2,5-di-tert.-amylhydroquinone,2,6-di-tert.-butyl-hydroquinone, 2,5-di-tert.-butyl-4-hydroxy-anisole,3,5-di-tert.-butyl-4-hydroxy-anisole, 3,5-di-tert.-butyl-4-hydroxyphenylstearate and bis-(3,5-di-tert.-butyl-4-hydroxyphenyl) adipate.

1.3 Hydroxylated thiodiphenyl ethers, such as, for example,2,2'-thio-bis-(6-tert.-butyl-4-methylphenol),2,2'-thio-bis-(4-octylphenol),4,4'-thio-bis-(6-tert.-butyl-3-methylphenol),4,4'-thio-bis-(3,6-di-sec.amylphenol),4,4'-thio-bis-(6-tert.-butyl-2-methylphenol) and4,4'-bis-(2,6-dimethyl-4-hydroxyphenyl) disulphide.

1.4 Alkylidene-bisphenols, such as, for example,2,2'-methylene-bis-(6-tert.-butyl-4-methylphenol),2,2'-methylene-bis-(6-tert.-butyl-4-ethylphenol),4,4'-methylene-bis-(6-tert.-butyl-2-methylphenol),4,4'-methylene-bis-(2,6-di-tert.butylphenol),2,6-di-(3-tert.-butyl-5-methyl-2-hydroxybenzyl)-4-methylphenol,2,2'-methylene-bis- 4-methyl-6 (α-methylcyclohexyl)-phenol!,1,1-bis-(3,5-dimethyl-2-hydroxyphenyl)-butane,1,1-bis-(5-tert.-butyl-4-hydroxy-2-methylphenyl)-butane,2,2-bis-(3,5-di-tert.-butyl-4-hydroxyphenyl)-propane,1,1,3-tris-(5-tert.-butyl-4-hydroxy-2-methylphenyl)-butane,2,2-bis-(5-tert.-butyl-4-hydroxy-2-methylphenyl)-4-n-dodecylmercaptobutane,1,1,5,5-tetra-(5-tert.-butyl-4-hydroxy-2-methylphenyl)-pentane andethylene glycol bis-(3,3-bis-(3'-tert.butyl-4'-hydroxyphenyl)-butyrate).

1.5 O-, N- and S-benzyl compounds, such as, for example,3,5,3',5'-tetra-tert.-butyl-4,4'-dihydroxydibenzyl ether, octadecyl4-hydroxy-3,5-dimethylbenzyl mercaptoacetate,tris-(3,5-di-tert.-butyl-4-hydroxybenzyl)-amine andbis-(4-tert.-butyl-3-hydroxy-2,6-dimethylbenzyl) dithioterephthalate.

1.6 Hydroxybenzylated malonate, such as, for example, dioctadecyl2,2-bis-(3,5-di-tert.-butyl-2-hydroxybenzyl)-malonates, dioctadecyl2-(3-tert.-butyl-4-hydroxy-5-methylbenzyl)-malonate,di-dodecylmercapto-ethyl2,2-bis-(3,5-di-tert.-butyl-4-hydroxybenzyl)-malonate anddi-(4-(1,1,3,3-tetramethylbutyl)-phenyl)2,2-bis-(3,5-di-tert.-butyl-4-hydroxybenzyl)-malonate.

1.7 Hydroxybenzyl-aromatic compounds, such as, for example,1,3,5-tri-(3,5-di-tert.-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene,1,4-di-(3,5-di-tert.-butyl-4-hydroxybenzyl)-2,3,5,6-tetramethylbenzeneand 2,4,6-tri-(3,5-di-tert.-butyl-4-hydroxybenzyl)-phenol.

1.8 s-Triazine compounds, such as, for example,2,4-bis-octylmercapto-6-(3,5-di-tert.-butyl-4-hydroxy-anilino)-s-triazine,2-octylmercapto-4,6-bis-(3,5-di-tert.-butyl-4-hydroxyanilino)-s-triazine,2-octylmercapto-4,6-bis-(3,5-di-tert.-butyl-4-hydroxyphenoxy)-s-triazine,2,4,6-tris-(3,5-di-tert.-butyl-4-hydroxyphenoxy)-s-triazine,2,4,6-tris-(3,5-di-tert.-butyl-4-hydroxyphenylethyl)-s-triazine and1,3,5-tris-(3,5-di-tert.-butyl-4-hydroxybenzyl) isocyanurate.

1.9 Amides of β-(3,5-di-tert.-butyl-4-hydroxyphenyl)-propionic acid,such as, for example,1,3,5-tris-(3,5-di-tert.-butyl-4-hydroxyphenyl-propionyl)-hexahydro-s-triazineandN,N'-di-(3,5-di-tert.-butyl-4-hydroxyphenyl-propionyl)-hexamethylenediamine.N,N'-(bis-β-(3,5-di-t-butyl-4-hydroxyphenyl)-propionyl)-hydrazine.

1.10 Esters of β-(3,5-di-tert.-butyl-4-hydroxyphenyl)-propionic acidwith monohydric or polyhydric alcohols, such as, for example, withmethanol, ethanol, octadecanol, 1,6-hexanediol, 1,9-nonmediol, ethyleneglycol, 1,2-propanediol, diethylene glycol, thiodiethylene glycol,neopentylglycol, pentaerythritol, 3-thia-undecanol, 3-thia-pentadecanol,trimethylhexanediol, trimethylolethane, trimethylolpropane,tris-hydroxyethyl isocyanurate and4-hydroxymethyl-1-phospha-2,6,7-trioxabicylo-(2,2,2)octane.

1.11 Esters of β-(5-tert.-butyl-4-hydroxy-3-methylphenyl)-propionic acidwith monohydric or polyhydric alcohols, such as, for example, withmethanol, ethanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethyleneglycol, 1,2-propanediol, diethylene glycol, thiodiethylene glycol,neopentylglycol, pentaerythritol, 3-thia-undecanol, 3-thio-pentadecanol,trimethylhexanediol trimethylolethane, trimethylolpropane,tris-hydroxyethyl isocyanurate and4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo(2,2,2)octane.

1.12 Esters of 3,5-di-tert.-butyl-4-hydroxyphenylacetic acid withmonohydric or polyhydric alcohols, such as, for example, with methanol,ethanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol,1,2-propanediol, diethylene glycol, thiodiglycol, neopentylglycol,pentaerythritol, 3-thia-undecanol, 3-thia-pentadecanoltrimethylhexanediol, trimethylolethane, trimethylolpropane,tris-hydroxyethyl isocyanurate and4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo (2,2,2)-octane, especiallythe tetra-bis ester of pentaerythritol.

1.13 Benzylphosphonates, such as, for example, dimethyl3,5-di-tert.-butyl-4-hydroxybenzyl-phosphonate, diethyl3,5-di-tert.-butyl-4-hydroxybenzyl-phosphonate dioctadecyl3,5-di-tert.butyl-4-hydroxybenzyl-phosphonate and dioctadecyl5-tert.-butyl-4-hydroxy-3-methylbenzyl-phosphonate.

The following may be mentioned as examples of further additives that canbe used together with the phosphite stabilizer of this invention and theantioxidant:

1. Aminoaryl derivatives, e.g. phenyl-1-naphthylamine,phenyl-2-naphthylamine, N,N'-diphenyl-p-phenylenediamine,N,N'-di-2-naphthyl-p-phenylenediamine,N,N'-di-2-naphthyl-p-phenylenediamine,N,N'-di-sec.-butyl-p-phenylenediamine,6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline,6-dodecyl-2,2,4-trimethyl-1,2-dihydroquinoline, mono- anddioctyliminodibenzyl, polymerized 2,2,4-trimethyl-1,2-dihydroquinoline.Octylated diphenylamine, nonylated diphenylamine,N-phenyl-N'-cyclohexyl-p-phenylenediamine,N-phenyl-N-'-isopropyl-p-phenylenediamine,N,N'-di-sect-octyl-p-phenylenediamine,N-phenyl-N'-sec.-octyl-p-phenylenediamine,N,N'-di-(1,4-dimethylpentyl)-p-phenylenediamine,N,N'-dimethyl-N,N'-di-(sec.-octyl)-p-phenylenediamine,2,6-dimethyl-4-methoxyaniline, 4-ethoxy-N-sec.-butylaniline,di-phenylamineacetone condensation product, aldol-1-naphthylamine andphenothiazine.

2. UV-Absorbers and light-stabilizing agents

2.1 2-(2'-Hydroxyphenyl)-benzotriazoles, e.g. The 5'-methyl-,3',5'-di-tert.-butyl-, 5'-tert.-butyl-, 5'-(1,1,3,3-tetramethylbutyl)-,5-chloro-3', 5-di-tert. -butyl-, 5-chloro-3'-tert.-butyl-5'-methyl,3'-sec.-butyl'5'-tert.-butyl-, 3'-α-methylbenzyl-5'-methyl-,3'-α-methylbenzyl-5'-methyl-5-chloro-, 4'-hydroxy-, 4'-methoxy-,4'-octoxy-, 3,5'-di-tert.-amyl-, 3'-methyl-5'-carbomethoxyethyl- and5-chloro-3',5'-di-tert.-amyl-derivative.

2.2 2,4-bis-(2'-Hydroxyphenyl)-6-alkyl-s-triazines, e.g. the 6-ethyl-,6-heptadecyl- or 6-undecyl-derivative. 2.3 2-Hydroxybenzophenones, e.g.the 4-hydroxy-, 4-methoxy-, 4-oxtoxy-, 4-decyloxy-, 4-dodocyloxy-,4-benzyloxy-, 4,2',4'-trihydroxy- or2'-hydroxy-4,4'-dimethoxy-derivative.

2.4 1,3-bis-(2'-Hydroxybenzoyl)-benzenes, e.g.1,3-bis-(2'-hydroxy-4'-hexyloxy-benzoyl)-benzene,1,3-bis-(2'-hydroxy-4'dodecyloxy-benzoyl)-benzene.

2.5 Esters of optionally substituted benzoic acids, e.g.phenylsalicylate, octylphenylsal icylate, dibenzoylresorcin,bis-(4-tert.-butylbenzoyl)-resorcin, benzoylresorcin,3,5-di-tert.-butyl-4-hydroxybenzoic acid-2,4-di-tert.-butylphenyl esteror -octadecyl ester or -2-methyl-4,6-di-tert.-butyl ester.

2.6 Acrylates, e.g. α-cyano-β,β-diphenylacrylic acid-ethyl ester or-isooctyl ester, α-carbomethoxy-cinnamic acid methyl ester,α-cyano-β-methyl-p-methoxycinnamic acid methyl ester or -butyl ester orN-(β-carbomethoxyvinyl) -2-methyl-indoline.

2.7 Sterically hindered amines, e.g.4-benzoyl-2,2,6,6-tetramethylpiperidine,4-stearyloxy-2,2,6,6-tetramethylpiperidine,bis-(2,2,6,6-tetramethylpiperidyl)-sebacate or3-n-octyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro(4,5)decane-2,4-dione.

2.8 Oxalic acid diamides, e.g. 4,4'-di-octyloxy-oxanilide,2,2'-di-octyloxy-5,5'-di-tert.-butyl-oxanolide.2.2'-di-dodecyloxy-5,5'-di-tert.-butyl-oxanilide,2-ethoxy-2'-ethyl-oxanilide, N,N'-bis-(3-dimethylaminopropyl)-oxalamide,2-ethoxy-5-tert.-butyl-2'-ethyl-oxanilide and the mixture thereof with2-ethoxy-2'-ethyl-5,4'-di-tert.-butyl-oxanilide, or mixtures of ortho-and paramethoxy- as well as of o- and p-ethoxy-disubstituted oxanilides.

3. Metal deactivators, e.g. oxanilide, isophthalic acid dihyrazide,sebacic acid-bis-phenylhydrazide, bis-benzylidene-oxalic aciddihydrazide, N,N'-diacetal-adipic acid dihydrazide,N,N'-bis-salicyloyloxalic acid dihydrazide,N,N'-bis-salicyloylhydrazine, N,N'-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hydrazine,N-salicyloyl-N'-salicylalhydrazine, 3-salicyloylamino-1,2,4-triazole orN,N'-bis-salicyloyl-thiopropionic acid dihydrazide.

4. Basic co-stabilizers, e.g. alkali metal salts and alkaline-earthmetal salts of higher fatty acids, for example Ca-stearate, Zn-stearate,Mg-behenate, Na-ricinoleate or K-palmitate.

5. Nucleation agents, e.g. 4-tert.-butylbenzoic acid, adipic acid ordiphenylacetic acid.

6. Phosphites, such as, for example, triphenyl phosphite, diphenylalkylphosphites, phenyldialkyl phosphites, tri-(nonylphenyl) phosphite,trilauryl phosphite, trioctadecyl phosphite,3,9-isodecyloxy-2,4,8,10-tetraoxa 3,9-diphospha(5,5)-undecane andtri-(4-hydroxy-3,5-di-tert.butylphenyl) phosphite.

Other additives that can be incorporated in the stabilized compositionsare optionally thiosynergists such as dilauryl-thiodiproprionate ordistearylthiodipropionate, lubricants such as stearyl alcohol fillers,carbon black, asbestos, lanolin, talc, glass fibers, pigments, opticalbrighteners, fireproofing agents and antistatic agents.

Polymeric particles may be coated with the present phosphites alone orin combination with other stabilizers for stabilization of the polymericmaterial. Particles may be spherical in shape and may be made byprocesses such as "Reactor Granule Technology" as disclosed in P. Galliand J. C. Halock, The Reactor Granule--A Unique Technology for theProduction of a New Generation of Polymer Blends, Society of PlasticsEngineers, Polyolefin III International Conference February 24-27, 1991and as disclosed in Pedrazzeth et al. U.S. Pat. No. 4,708,979 entitledProcess for the Stabilization of Spherically Polymerized Polyolefins,issued Nov. 24, 1987, both of which are disclosed herein by reference.Particle formation may be achieved by support Ziegler-Natta Catalystsystems. Suitable commercial processes are known by the trademarks:Spheripol, Addipol and Spherilene.

EXAMPLES ##STR7##

                  TABLE 1                                                         ______________________________________                                        Example   Phos          T1/2   UVY                                            ______________________________________                                        A         PHOS 1         4     No                                             B         PHOS 2        15     Yes                                            C         PHOS 3        22     Yes                                            1         PHOS 4         64+   No                                             ______________________________________                                         T 1/2 is the in-polymer (polypropylene) hydrolytic stability of the            phosphite at 60° C./75% relative humidity in days to loss of 50% of     the phosphites. UVY indicates whether the phosphite turned yellow under        ultraviolet light. Examples A-C are comparative examples. Example 1            illustrates the enhanced hydrolytic stability and resistance to                ultraviolet light yellowing of the phosphite present invention.           

I claim:
 1. A thermoplastic composition comprising a thermoplasticpolymer and a phosphite of the formula ##STR8## wherein each R⁴ ishydrogen, each R⁵ is independently selected from the group consisting ofalkyl radicals of one to six carbon atoms, each R⁶ is a tertiary butylradical, R⁷ is a divalent alkylidene radical having from 1 to 6 carbonatoms and wherein said phosphite is present in an amount effective toenhance the thermal oxidative stability of said composition.
 2. Thecomposition of claim 1 wherein said phosphite is present at a level offrom 0.01 to 1 percent by weight based on the total weight of thecomposition.
 3. The composition of claim 2 wherein said thermoplasticpolymer is polypropylene.
 4. A thermoplastic composition consistingessentially of a thermoplastic polymer and a phosphite of the formula##STR9## wherein each R⁴ is hydrogen, each R⁵ is independently selectedfrom the group consisting of alkyl radicals of one to six carbon atoms,each R⁶ is a tertiary butyl radical, R⁷ is a divalent alkylidene radicalhaving from 1 to 6 carbon atoms and wherein said phosphite is present inan amount effective to enhance the thermal oxidative stability of saidcomposition.
 5. The thermoplastic composition of claim 1, wherein eachR⁵ is a methyl group.
 6. The thermoplastic composition of claim 4,wherein each R⁵ is a methyl group.
 7. The thermoplastic composition ofclaim 1, wherein the phosphite has the formula: ##STR10##
 8. Thethermoplastic composition of claim 4, wherein the phosphite has theformula: ##STR11##
 9. The thermoplastic composition of claim 1, whereinthe phosphite is present at a level from about 0.01 to about 5% byweight based upon the total weight of the composition.
 10. Thethermoplastic composition of claim 1, wherein the phosphite is presentat a level from about 0.05 to about 2% by weight based upon the totalweight of the composition.
 11. The thermoplastic composition of claim 1,wherein the thermoplastic resin is a polyolefin resin.
 12. Thethermoplastic composition of claim 4, wherein the thermoplastic resin isa polyolefin resin.
 13. The thermoplastic composition of claim 1,wherein the thermoplastic resin is selected from the group consisting ofpolystyrene, impact polystyrene, ABS resin, SBR, isoprene, naturalrubber, polyesters, polyurethanes, polycarbonates, polyamides,copolyamides, and polysulfones.
 14. The thermoplastic composition ofclaim 4, wherein the thermoplastic resin is selected from the groupconsisting of polystyrene, impact polystyrene, ABS resin, SBR, isoprene,natural rubber, polyesters, polyurethanes, polycarbonates, polyamides,copolyamides, and polysulfones.
 15. The thermoplastic composition ofclaim 1, further comprising at least one optional additive of the groupconsisting of thiosynergists, lubricants, carbon black, lanolin, talc,glass fibers, pigments, optical brighteners, fireproofing agents, andantistatic agents.
 16. The thermoplastic composition of claim 4, furtherconsisting essentially of at least one optional additive of the groupconsisting of thiosynergists, lubricants, carbon black, lanolin, talc,glass fibers, pigments, optical brighteners, fireproofing agents, andantistatic agents.
 17. The thermoplastic composition of claim 1, furthercomprising a phenolic antioxidant and a neutralizer.
 18. Thethermoplastic composition of claim 4, further consisting essentially ofa phenolic antioxidant and a neutralizer.